Touch panel display systems (also commonly known, for example, as touch screens systems) can allow a user to touch on or near an area of a touch panel (also commonly referred to as a touch screen) to enter a command to a computer system and, thereby, control the operation of the computer system. Touch panel display systems can provide an intuitive method by which people can easily interact with and control various functions performed by a computer system. For example, a touch panel display system can display icon elements representing a keyboard to allow a user to input text to a computer system. Such interactive graphical representations of a keyboard or other information can eliminate the need to configure a computer system with certain other input devices, such as a keyboard or mouse.
Touch panels can be produced in a variety of types and sizes and can be used as part of a wide variety of systems, such as kiosks, personal computer systems, portable consumer electronics (e.g., cellular telephones, personal digital assistants, hand held computers, video game devices, etc.), domestic appliances, vehicles information systems (e.g., GPS locators), and industrial equipment and tools. Businesses can use touch panel display systems to display information to potential customers and to receive feedback or commands from customers regarding information they desire. Touch panel display systems can also be used to facilitate business and/or consumer transactions, such as banking or the sale of merchandise or services. Earlier prior art approaches to touch panel display systems typically operated based on principles such as capacitance, resistance, or acoustic waves. More recent prior art approaches to touch panel display systems operate based on detection of emitted energy (e.g., infrared energy) and image processing, which can often be more accurate and reliable than the earlier prior art approaches.
One recent approach to touch panel display systems involves the detection of light emitted across a touch panel surface from an oscillating or rotating emission system, such as a fixed emitter and an oscillating or rotating reflector. A similar approach involves the detection of light emitted across a touch panel surface by an oscillating or rotating detector assembly. In either of these approaches, a user's touch is detected based on the interruption of the light emitted across the touch panel surface. However, these approaches rely on moving components, which are susceptible to mechanical failure, can decrease the detection accuracy of a user's touch, and lead to increased production costs and times.
Another recent approach to touch panel display systems involves the use of video cameras positioned behind the touch panel to detect light internally reflected within the touch panel. A touch, resulting from a user placing a finger or rubbery object directly on the touch panel surface, interrupts the internal reflection of light in the touch panel and causes a bright or dark image to appear on the touch panel, which is detected by the video camera. A user's touch of the touch panel will typically not be detected by this approach if it is made with less than firm contact by a finger or by an object of less than sufficient density. Furthermore, this approach involves video imaging, which usually requires expensive imaging components and complicated processing operations to detect the location of a touch on the touch panel. Additionally, the need to position the video camera behind the touch panel can make the display system bulky and limit its application.
Yet another recent approach to touch panel display systems involves the use of video cameras to acquire real-time images of the user touching on or near the touch panel surface. Such images are then processed to determine the location of the user's touch in relation to the touch panel. Touch panel display systems based on this approach usually also require expensive video imaging components and complicated processing operations to detect a touch location. Furthermore, the accuracy of these video-based systems can be sensitive to variations in the surrounding light levels (e.g., ambient light levels), which can further complicate the processing required to detect a touch. Moreover, this approach typically requires video cameras to be positioned on multiple sides of a touch panel display system in order to provide accurate touch detection, which usually also increases the production cost.
Accordingly, there remains a need in the art for a touch panel display system that can accurately detect a user's touch on or near a touch panel surface, but is less expensive and time consuming to produce as compared to existing approaches. There is also a need in the art for a touch panel display system that can be implemented with less expensive components and less complicated processing operations to detect touch location. There furthermore is a need in the art for a touch panel display system that can detect a touch without the need to position energy emission and/or detection components on multiple sides of a touch panel, thereby reducing the size of the system. Moreover, there is a need in the art for a touch panel display systems that has reduced sensitivity to variations in surrounding light levels, thereby further simplifying the processing operations to detect a touch.